Water level indicators having a remote fiber optic readout display are well-known. An example of such a device may be seen in U.S. Pat. No. 3,713,338. In such devices the water level optical signal is focused on one end of a fiber optic assembly and is transmitted along a significant length of the fiber optic assembly to a remote readout area where the other end of the fiber optic assembly terminates.
In certain situations a local readout of the water level signal is desired in addition to the remote readout display. For such situations a beam splitter is used for the optical signal indicative of water level with the beam splitter transmitting the majority of the optical signal to a single fiber optic assembly of extended length which provides the remote readout of the water level signal. A small portion of the optical signal is reflected by the beam splitter directly to a glass diffuser screen which screen provides the local readout of the optical signal indicative of water level. The optical signal indicative of water level is focused directly on the end of the single remote readout fiber optic assembly. This significantly increases the available light provided to the remote readout fiber optic assembly and thus compensates for the losses suffered by the signal going through the extended length of the fiber optic assembly.
In such units it is very desirable to align the remote fiber optic cable with the axis of the illuminator to provide a maximum of illumination to the fiber optic cable. Such alignment could be done by actual measurements of the distances between the illuminator and the fiber optic cable with reference to some standard reference point or points. However, this is time-consuming and inaccurate.